Boundless Informant The National Security Agency's internal analytic tool that allows it to monitor surveillance country by country and program by program.

Bruneau (or Hemlock)The codenames given to the Italian embassy in Washington by the NSA.

Bluf Stands for "bottom line up front" – a request from NSA analysts to collect less data from the Muscular program (see below) because it is of no intelligence value.

Bullrun The NSA's efforts to undermine encryption technology that protects email accounts, banking transactions and official records. The UK has a similar programme, with both codenamed after civil war battles: Bullrun for the NSA and Edgehill for GCHQ.

Cheesy Name A GCHQ program that selects encryption keys that might be vulnerable to being cracked.

Dishfire Database that stores text messages, for future use.

DNI (digital network information) Data sent across computer networks, such as web page requests, emails, voice over IP. (Formally, any information sent as "packets").

DNR (dialled number records) The metadata around phone calls, including the sending and receiving of phone numbers, call time and duration.

Dropmire A surveillance method that involves bugging encrypted fax machines. Used to spy on the European Union embassy in New York.

Edgehill See Bullrun.

Fisa court (Fisc) The foreign intelligence surveillance court, a secret US court which oversees surveillance under the Fisa Act.

Fairview See Upstream.

Five Eyes Britain, the US, Canada, Australia and New Zealand – the club of English-speaking countries sharing intelligence.